1. Field of the Invention
The present invention relates to a mobile packet communication system and a path setting method in a mobile packet communication network in which a mobile packet terminal moves through different radio zones.
2. Description of the Related Art
FIG. 8 is a conceptual drawing for explaining a conventional mobile packet communication system in which a mobile packet terminal moves from one radio zone to another. Referring to FIG. 8, the following outlines mobile packet communications in the conventional mobile packet communication system.
It is assumed that the mobile packet communication system in the figure has a mobile radio communication network 86, which is connected to an external communication network 85. In the shown example, the mobile radio communication network 86 is provided with a plurality of radio zones 81 and 82 by respective base stations 87 and 88. The base station 87 is connected to a mobile network exchange 89, which is connected to an external communication network 85 via a radio terminator 83. Similarly, the base station 88 is connected to a mobile network exchange 90, which is connected to the external communication network 85 via a radio terminator 84.
Suppose that a mobile packet terminal 80 roams from the radio zone 81 to the radio zone 82. When the mobile packet terminal 80 is not present in the radio zone 81, the base station 87 notifies the mobile network exchange 89 of the information (mobile packet terminal absence information). In response to the mobile packet terminal absence information, the mobile network exchange 89 disconnects the path connecting the external communication network 85 and the mobile packet terminal 80.
On the other hand, when the mobile packet terminal 80 appears in the radio zone 82, the base station 88 recognizes the mobile packet terminal 80 and notifies the mobile network exchange 90 of the information (mobile packet terminal appearance information). In response to the mobile packet terminal appearance information, the mobile network exchange 90 establishes a path connecting the external communication network 85 and the mobile packet terminal 80.
By the way, in a conventional mobile packet communication system, there exists a problem that packet communications are disabled from the time the previous path is disconnected until a new path is established, if, for example, a mobile packet terminal is performing packet communications actively when the mobile packet terminal is moving across radio zones.
An object of the present invention is to provide a mobile packet communication system which can perform secure packet communications even when the mobile packet terminal is moving across radio zones.
According to the present invention, there is provided a path setting method in mobile packet communications wherein at least one mobile packet terminal is provided, and a plurality of radio zones are specified, and repeater sections corresponding to the radio zones are provided for connecting an external communication network and the radio zones, each of the repeater sections comprises base stations for performing packet communications by using the mobile packet terminals and radio links, mobile network exchanges connected to the base stations, and radio terminators connected to the mobile network exchange and which terminate a radio section protocol to connect to the external communication network, the path setting method being characterized in that the mobile network exchanges are connected to each other and each of the radio terminators controls setting a path from the base station in the radio zone in which the mobile packet terminal is located to either of the radio terminators according to the packet communication state of the mobile packet terminal when the mobile packet terminal roams across the radio zones.
For example, when the mobile packet terminal roams in the active state from the first radio zone to the second radio zone, the radio terminator corresponding to the first radio zone controls the mobile network exchange in the first radio zone to set a path across the mobile network exchange in the first radio zone and the mobile network exchange in the second radio zone and to establish a path connection across the mobile packet terminal and the radio terminator corresponding to the first radio zone.
Also, when the mobile packet terminal roams in the dormant state from the first radio zone to the second radio zone, the radio terminator corresponding to the first radio zone controls the mobile network exchange in the first radio zone to disconnect the path connecting the mobile network exchange in the first radio zone and the base station in the first radio zone and controls the mobile network exchange in the second radio zone to set a path across the mobile packet terminal and the radio terminator corresponding to the second radio zone.
Moreover, when the mobile packet terminal roams in the active state from the first radio zone to the second radio zone and the mobile packet terminal makes transition to the dormant state, the radio terminator corresponding to the first radio zone, recognizing the active state, controls the mobile network exchange in the first radio zone to set a path across the mobile network exchange in the first radio zone and the mobile network exchange in the second radio zone and to establish a path connection across the mobile packet terminal and the radio terminator corresponding to the first radio zone, and the radio terminator, recognizing the dormant state, controls the mobile network exchange in the first radio zone to disconnect the path connecting the mobile network exchange in the first radio zone and the base station in the first radio zone and controls the mobile network exchange in the second radio zone to set a path across the mobile packet terminal and the radio terminator corresponding to the second radio zone.
Further, when the mobile packet terminal roams from the first radio zone to the second radio zone, the radio terminator corresponding to the first radio zone may control the mobile network exchange in the first radio zone to set a path across the mobile network exchange in the first radio zone and the mobile network exchange in the second radio zone and to establish a path connection across the mobile packet terminal and the radio terminator corresponding to the first radio zone, and after that, the radio terminator may supervise packet communication state of the mobile packet terminal to judge whether or not the packet communication state of the mobile packet terminal is the dormant state, and if the packet communication state of the mobile packet terminal is the dormant state, the radio terminator may control the mobile network exchange in the first radio zone to disconnect the path connecting the mobile network exchange in the first radio zone and the base station in the first radio zone and control the mobile network exchange in the second radio zone to set a path across the mobile packet terminal and the radio terminator corresponding to the second radio zone.